ESA sets date for dramatic end to Rosetta's mission

ESA has announced the date upon which mission
operators will crash the Rosetta spacecraft into the surface of the
comet 67P/Churyumov–Gerasimenko. Unlike its now-sleeping
companion, the Philae lander, there is no hope that once the
spacecraft touches down on the surface of 67P, the science team
will be able to re-establish contact with the legendary probe.

ESA was not slow to pull on the heartstrings,
releasing cartoon after cartoon that succeeded in anthropomorphizing
the remote explorers. The combination of a well-executed public
awareness campaign coupled with the ambitious nature of the endeavour
succeeded in capturing the public's attention in a way that few
unmanned missions have managed before.

Unfortunately, as with all great things, Rosetta's
mission must come to an end. The spacecraft is currently riding 67P
out towards the orbit of Jupiter. At its furthest point, the probe
will be some 850 million km (553 million miles) distant from the Sun.
At this range, Rosetta will lack the bandwidth to transmit scientific
data, and will be unable to gather enough precious starlight to power
its systems. Returning the spacecraft to a state of hibernation is
not an option, as the probe's heaters would almost certainly fail,
preventing it from ever awakening.

Graphic displaying the predicted position of Rosetta (displayed as a red line) on Sept. 30th, 2016(Credit: ESA)

Instead of risking this almost certain anaemic
demise, the Rosetta team have elected to have Rosetta go out in a
blaze of glory, by sending to probe to join Philae on the surface of
67P, with a preliminary date set for the 30th of
September. According to Rosetta's handlers, the spacecraft's descent
is likely to be far more challenging than that faced by Philae in
November 2014.

The danger for
Rosetta is not the force of landing, but rather the influence of the
comet during the final six weeks prior to the collision. During this
period, the probe will be more susceptible to the gravitational
influence of the irregularly shaped comet. This could lead to
deviations in Rosetta's trajectory – a significant problem for a
spacecraft traversing a tight, eccentric orbit around an
unpredictable comet. To keep Rosetta safe, mission operators will be
forced to upload course corrections on a more regular basis.

Rosetta has coped with debris thrown out by the comet since its arrival in orbit in August 2014(Credit: ESA/Rosetta/MPS for OSIRIS Team MPS/UPD/LAM/IAA/SSO/INTA/UPM/DASP/IDA)

The team is set
to begin tweaking Rosetta's trajectory starting in August, with a
final course correction scheduled for 12 hours before impact. If all
goes well, Rosetta will touch down on 67P at a mere 50 cm per second
– roughly half the speed at which Philae first collided with the
comet. On the way down, Rosetta will be firing on all cylinders,
collecting as much high-res imagery and scientific data as possible,
before ending its 12-year journey in space by coming to rest on the
surface of the comet it had spent its life documenting.

"We're trying to squeeze as many observations
in as possible before we run out of solar power," comments Matt
Taylor, ESA Rosetta project scientist. "30 September will mark the
end of spacecraft operations, but the beginning of the phase where
the full focus of the teams will be on science. That is what the
Rosetta mission was launched for and we have years of work ahead of
us, thoroughly analysing its data."